NMR Multi-Time Correlation Functions of Ion Dynamics in Solids

Abstract

We show that NMR multi-time correlation functions provide interesting new insights into the nature of lithium and silver ion dynamics in solids. For solid ion conductors, they usually probe the elementary jumps of the long-range charge transport. NMR two-time correlation functions yield rates and activation energies of the ionic hopping motion. Moreover, they reveal that the ionic relaxation exhibits a strong nonexponentiality in the studied crystals and glasses. NMR three-time correlation functions enable quantitative determination of the origin of the nonexponentiality. For various solid-state electrolytes, the analysis shows that pronounced dynamical heterogeneities govern the ionic hopping motion. If dynamical heterogeneities exist, NMR four-time correlation functions allow one to measure the time scale of exchange processes within the rate distributions. For silver ion dynamics in a crystalline and a glassy material, the results indicate that initially slow ions exhibit random new rates from broad rate distributions after very few jump events.

Relation of short-range and long-range lithium ion dynamics in glass-ceramics: Insights fromLi7NMR field-cycling and field-gradient studies

“…7 Li NMR is a powerful tool for this purpose. [9][10][11][12] Combining various 7 Li NMR methods, it is possible to investigate lithium ion jump motion in a broad time window, covering roughly ten orders of magnitude. In particular, 7 Li spin-lattice relaxation (SLR) analysis has a long-standing tradition in studies of local lithium ion dynamics in solid electrolytes.…”

From Micro to Macro: Access to Long‐Range Li+ Diffusion Parameters in Solids via Microscopic 6, 7Li Spin‐Alignment Echo NMR Spectroscopy

“…In the present Minireview we will show how this can be achieved by using newly established 6,7 Li spinalignment echo (SAE) NMR spectroscopy. [30,[36][37][38][39][40][41][42][43][44] So far, a number of polycrystalline and glassy materials have been investigated by SAE NMR spectroscopy. [30,[36][37][38][39][40][41][42][43][44] Interestingly, in many cases the results are fully consistent with those obtained from macroscopic techniques, [41,45] such as field-gradient NMR or dc-conductivity measurements.…”

Communication: Heterogeneous water dynamics on a clathrate hydrate lattice detected by multidimensional oxygen nuclear magnetic resonance

“…12 Furthermore, with dipolar interactions of several kHz present in our sample, 12 the limit of inexact restoration of the NMR frequencies is fulfilled for the evolution times chosen for the present study. 22 A Kohlrausch fit to the F 2 function, shown as a solid line in Fig. 4, yields a characteristic time scale of τ 2 = 0.58 ± 0.04 ms and a stretching parameter β = 0.51 ± 0.03.…”

“…for the inexact restoration of NMR frequencies 22 that is relevant in the present situation. For the data shown in Fig.…”

“…However, so far filtering experiments were reported solely for spin-1/2 or spin-1 nuclei such as 2 H, 6 Li, 13 C, and 109 Ag. [19][20][21][22][23] Only recently, we succeeded to perform these kinds of experiments also for nonselectively excitable I = 3/2 nuclei like 7 Li. 24 For the present work, we designed and performed a dynamic filtering experiment that is applicable to any half-integer quadrupolar probe, provided its NMR spectrum is broad enough so that only its central ( 1 /2 ↔ + 1 /2) transition can be excited selectively.…”